DALLAS A shadowy Mexican drug gang that sprang from the Texas-Mexico border region just a dozen years ago has made North Texas a key hub in a criminal enterprise that now extends through Central America and into Colombia, law enforcement officials say.

The notoriously brutal group known as the Zetas has used family and personal connections to make the Dallas area into a sophisticated distribution point, moving cocaine, pot and methamphetamine to other U.S. markets and sending weapons, ammunition and millions of dollars in bulk cash back to Mexico, authorities say.

Developments in the last couple months underscore the region’s role in an increasingly dangerous criminal network. On Feb. 15, Texas-based U.S. Immigration and Customs Enforcement agent Jaime Zapata was fatally shot and his partner wounded after their armored vehicle was forced off a busy highway in central Mexico. The gunmen were members of the Zetas, investigators said, and one of the weapons used came from a North Texas gun shop.

In response to the shooting, U.S. law enforcement officials led a massive sweep throughout the country and Latin America against Mexican cartel suspects. Dallas-based agents arrested 57 people and seized more than $2 million in cash, gold and other property.

“Dallas is no longer a world away from the border,” said Jeffrey Stamm, assistant special agent in charge of the Drug Enforcement Administration’s Dallas office, describing the Dallas area as a key base for the Zetas and other cartels. “We are close enough to be the command-and-control center.”

Over several months, a team of Dallas Morning News journalists examined the Zetas’ role in the multibillion-dollar illegal drug trade, interviewing dozens of law enforcement officials and others with knowledge of the group in Mexico, Colombia, Guatemala and Texas. Among their findings:

The Zetas have built alliances with gangs in Central America, particularly Guatemala, adding to the violence and corruption afflicting that region and further empowering those groups to spread lawlessness and terror among the population. The Zetas also have gained control of large pieces of land in Guatemala, compromising border security and facilitating smuggling, and have made inroads into Colombia, gaining direct access to producers and smugglers.

The Zetas have become one of the most brutal and powerful criminal organizations in Mexico, wresting territory from rival groups and corrupting, intimidating and co-opting law enforcement authorities, politicians and others, especially along the border with Texas.

The impact of the Zetas and other criminal groups in North Texas is on display daily in Dallas drug courts, where addicts struggle to repair their damaged lives and step away from the criminal lifestyle that almost always accompanies their drug use.

The Zetas’ presence in Dallas, first documented in The Dallas Morning News in 2005, has continued to grow because of the area’s confluence of bustling highways, a busy international airport and the familiarity of a large Hispanic immigrant community. Its leaders are known to have relatives here, authorities say.

But the organization is hardly local. Over the years, through violence and networking, it has extended its reach throughout Mexico and into Central and South America. In 2009, President Barack Obama named the Zetas a Specially Designated Narcotics Trafficker Kingpin organization, reserved for the world’s most dangerous drug organizations.

“The reach of Mexican organized crime spreads across the globe,” said expert Edgardo Buscaglia, who has advised the United Nations on drug policy and teaches at the Autonomous Institute of Technology of Mexico in Mexico City. “They’re powerful, deadly and have proven they’re capable of paralyzing governments, including regions throughout Mexico. Calling them (simply) drug traffickers is no longer accurate. They’re some of the world’s most powerful organized crime members.”

The Zetas are known for bringing an especially brutal brand of violence to the borderlands just south of Texas. In August, after gunmen massacred 72 migrants, mostly from Central America, a survivor of the bloodbath said the killers identified themselves as Zetas.

“You have Mexican cartels, and then you have terrorists,” said a U.S. federal agent with expertise in gathering intelligence on the Zetas, speaking on condition of anonymity. “The Zetas are terrorists, not a cartel.”

The Zetas have transformed two Mexican states bordering Texas, Tamaulipas and Nuevo Leon – including the key industrial city of Monterrey – into a bloody war zone as they have battled their former employers, the Gulf cartel, for control of the territory, law enforcement officials say.

Journalists have been killed or intimidated into silence. Police officers have been killed and corrupted. Politicians have been slain. Entire communities have been evacuated as residents flee for their lives.

Such wholesale bloodletting doesn’t yet characterize the Zetas’ presence in North Texas, although several recent killings carried the hallmarks of cartel violence. But here, as in Mexico, competition among cartels could take a turn for the worse, authorities say.

“I’m not going to predict street violence and turf battles on the streets of Dallas,” said Stamm of the DEA. “There is a fair bit of caution with … these organizations to not mess where they eat in the U.S. distribution markets. But certainly there is a power struggle. … It’s anybody’s guess how that’s going to end, and how much more violence will occur along the way.”

Currently, the Zetas are pitted against a confederation of rival groups, known as Narcos Unidos, which joined forces in an effort to counter the growing power of the Zetas, authorities say.

The Zetas originated as the Mexican military’s version of the U.S. Army’s Special Forces. Known in Mexico by the acronym of GAFES, for Grupo Aeromovil de Fuerzas Especiales (Special Forces Air Mobile Group), they were tasked with taking down the country’s burgeoning drug cartels.

Members of the unit received training at U.S. military bases, according to a database created through military reports to Congress by the Washington Office on Latin America, a think tank.

At least 35 of those original GAFES members switched sides, authorities say, joining the narcotics trafficking force of Osiel Cardenas and becoming armed enforcers for his Gulf cartel, named for its home base near the Gulf of Mexico and just south of Brownsville.

The paramilitary group flourished, eventually growing to more than 1,000 members and breaking away from the Gulf cartel to go into business for itself, according to the federal agent and Zetas expert.

A Mexican intelligence official, speaking on condition of anonymity, played down the role of U.S. training as some of the original GAFES members formed the nucleus of the Zetas.

“Who trained who is irrelevant,” the official said. “The fact is the Zetas, whether trained directly or indirectly by U.S. Special Forces … have become force multipliers. They’re terrorizing our country and represent the biggest threat to the country’s national security.”

The organization is equal parts commando brigade, intelligence service, public relations firm and Fortune 500 company. Workers are drawn extensively from family, making it difficult for law enforcement to infiltrate. “It’s like the mafia,” Stamm said. “You’re going to utilize people you know.”

Its members arm themselves in large part from a steady supply of thousands of military-style guns, including long-range .50-caliber rifles, from Texas and other U.S. border states to get around stiff Mexican gun laws.

The cartel’s chief engineer, who was arrested in 2008 and charged in Houston, built and ran a sophisticated communication network throughout Mexico using short-distance walkie-talkies to avoid wiretaps, court documents show. He also set up covert camera systems throughout Mexico to spy on authorities’ activities.

The group has a sophisticated record-keeping system using laptops and flash drives, authorities say. Members keep databases of cocaine shipment amounts, identities of bosses over smuggling routes, payroll, payments made to law enforcement officials, and money received and owed, according to a federal indictment of the group pending in Washington, D.C.

The group uses a range of media to present itself to the public. It hung banners in Nuevo Laredo in 2008 seeking soldiers to join its ranks. Videos of some of the group’s beheadings can be found online. Some cartel trucks and SUVs in Mexico are adorned with painted “Z”s, an open challenge to Mexican military forces battling them.

To protect its cash flow from volatility in the international drug market, the cartel has diversified in recent years, ramping up ransom kidnappings for cash and stealing more than $1 billion worth of oil from Mexican pipelines, authorities say.

While the group is highly organized, Stamm cautions against thinking of the organization as a traditional business with a set payroll and logistics costs. “A drug trafficking organization can promise payment to a transporter and just not pay. And if he complains, they kill him,” he said.

Slaughtering rivals or out-of-line employees and their relatives is the norm. A former assassin told the Brownsville Herald in February that he killed 32 people for the Zetas. To fortify himself before a hit – which often ended with cutting up the body and scattering its pieces – he and his cohorts would drink whiskey or snort cocaine.

As the Zetas have battled the Gulf cartel for dominance of the region bordering South Texas, they have expanded their reach into Central and South America.

The U.S. Bureau of International Narcotics and Law Enforcement Affairs, an arm of the State Department, concluded in a March 2010 report that “entire regions of Guatemala are now essentially under the control” of drug-trafficking organizations, “the most visible of which is the Mexican group known as the Zetas.”

In Colombia, where the U.S.-backed government has succeeded in smashing that country’s most notorious cartels, the Zetas have stepped in to deal directly with coca growers, U.S. and Colombian officials say.

The Mexican group also uses Venezuela as a springboard to move the product northward, using fast boats to Panama and small planes to Honduras and Guatemala, the officials say.

It is difficult to know the extent of the Zetas’ presence in North Texas, but there are signs that it is substantial.

The organization’s reputed No. 2 leader, Miguel Trevino Morales, grew up in the area and was arrested in Dallas when he was a teenager before he began his cartel career. He still has family here, authorities say. He is under federal indictment in the Eastern District of New York and Washington, D.C. The State Department is offering a $5 million reward for information leading to his arrest and conviction.

In 2009, the U.S. Treasury’s Office of Foreign Assets Control named Morales a Specially Designated Narcotics Trafficker through the Foreign Narcotics Kingpin Designation Act, making him one of the world’s most wanted narco-traffickers. The designation freezes any assets he has in this country and imposes more than a $1 million fine on anyone doing business with him.

He was the chief target in a massive law enforcement sweep in North Texas and throughout the U.S. and Latin America in late February following the death of ICE agent Zapata.

Another man alleged to be a member of the Zetas actually attended Dallas-area public schools, law enforcement officials say.

The man, Sigifredo Najera Talamantes, was arrested last year in northern Mexico and accused of a 2008 gun and grenade attack against the U.S. Consulate in Monterrey, two hours south of Laredo.

Clues about the group’s local activities come from federal criminal cases involving Zetas cell leaders as well as lower-level drug and gun smugglers.

In 2009, for example, the FBI and other law enforcement agents busted a cocaine ring in a case that was linked to the Zetas, who “kidnapped” a Farmers Branch man with a trucking firm who had worked with them, according to court records.

Gabriel Mendoza Sr., 60, the owner of Gabriel’s Trucking, pleaded guilty in February 2010 to conspiracy to distribute drugs and to commit money laundering. His son, Gabriel Mendoza Jr., 40, admitted he conspired to distribute cocaine from Mexico.

According to the court record, Mendoza Sr. was kidnapped in early 2009 in a Mexican border town by the Zetas, described as a “paramilitary organization that enforces the drug taxes.” Mendoza agreed to do further work for the Zetas, moving money south.

The court record describes how drugs were smuggled north from Mexico and how hundreds of thousands of dollars were moved south in a truck registered to the senior Mendoza. A transcript of a deposition also said the company recruited truck drivers to transport cocaine and methamphetamine.

Prosecuting attorney Heather Rattan said Mendoza testified that “when you start working for them, you can’t get out because basically they own you.”

In February, a Fort Worth gun dealer called the Bureau of Alcohol, Tobacco, Firearms and Explosives to report that suspicious men had paid cash for 27 military-style rifles. Agents arrested two of the men, Jayson Beltram and Eliseo Valverde Jr. According to court documents, they told agents that they got $20,000 from a Zetas contact in Grand Prairie to buy the weapons to be smuggled to Mexico.

In interviews with two reporters, a person with knowledge of the Zetas described in general terms the group’s North Texas operations, including money laundering in businesses such as restaurants, car lots and meat markets. The source also said there were warehouses from which loads of drugs were trucked to places including Kansas, Oklahoma, Minnesota, Atlanta and Chicago.

The source said scores of Texans were employed to transport high-powered weapons and bags of cash back into Mexico in hidden compartments of their vehicles.

Another person with knowledge of the Zetas recounted a case in which so many bundles of cash were stuffed into the gas tank of a vehicle that the driver had to stop every 50 miles to refuel.

That source, interviewed in Ciudad Aleman, Mexico, said the vehicle was driven by an American retiree eager to earn extra cash on his monthly trek to a Mexican pharmacy to buy his blood-thinning prescription and to visit a dentist.

The source said dozens of people traveled the same route weekly.

While fear of spillover violence is usually focused on border cities, El Paso, Laredo, McAllen, Tucson and San Diego actually rank among the safest cities in the U.S.

Federal authorities are more concerned about violence in key distribution points such as Dallas, Houston and Atlanta.

Bruce Bagley, a political science professor at the University of Miami, estimates that dozens of recent killings in cities around the U.S. are tied to cartels.

“White powder, dope, heroin doesn’t just magically appear in the streets of Dallas, New York or Miami,” he said. “You need a network, and there are consequences, like people killing each other on both sides of the border.”